The present invention relates generally to the adjustment in location of pull-type implements and, more specifically, to an apparatus mounted on a prime mover pulling an implement that will laterally shift the position of the implement relative to the prime mover in response to a localization signal so as to reliably maintain a preselected path.
The practice of precision farming was made possible by the advent of global navigation satellite systems (referred to in the U.S. as GPS). Using GPS-enabled equipment, a farmer can locate a precise position in a field which allows for the creation of maps of the spatial variability of as many variables as can be measured, e.g. crop yield, topography, organic matter content, moisture levels, nitrogen levels, pH, and the like. Manufacturers of precision farming equipment have begun to provide automated steering systems that use the GPS signals to steer a prime mover, such as a tractor, over a predetermined path. While such equipment functions well to reliably and accurately guide the prime mover, variations in soils and topography limit the reliable and accurate positioning of implements pulled by the prime mover.
There have been several attempts in the art to address this issue. One attempt is to provide a steerable unit that moves the implement laterally of the prime mover so that the implement follows the desired path even if the prime mover strays off of the path due to changes in the soil or topography. Another attempt uses a shifting apparatus mounted on the prime mover for laterally shifting the implement to achieve the same result. Yet another attempt modifies the implement hitch to laterally move the working part of the implement relative to the hitch again to achieve the same result.
Each of these attempts have drawbacks. Moving the tractor does not provide sufficient responsiveness to address high frequency changes caused by non-homogenous soil conditions or when there are variations in the topography, such as changing side slope angles. Steering the implement requires expensive and complex equipment and is not always practical, particularly where the implement has coulters or other ground-engaging structures. Such systems often only steer the implement when it is engaged in the ground and so miss the opportunity to guide the implement prior to entry into the ground to ease field entry and line acquisition. Shifting the implement tongue such as proposed by several manufacturers, including MDW, Navigation, Fleischer Manufacturing and Eco-Dan, or as described in European Patent No. EP 2283719, reduce the tractor's versatility, for example by requiring removal of the draw bar or preventing use of a power-driven implement, and negatively impact the weight distribution by moving the load carried by the tractor away from the rear axle.
Accordingly, there is a need for an apparatus that will provide for lateral shifting of a pulled implement so that is will reliably and accurately follow a prescribed path and which will not limit the versatility of the prime mover being used to pull the implement.